In the production of extruded bodies, generally hollow or shaped bodies such as window or frame members, tubes or the like, hereinafter referred to variously as an extrudate, an extruded body, an extruded profile or an extruded shape, the extrusion with pliable and plastically deformable walls emerges from an extrusion die of a plastifying device or extruder and can be passed to a calibrating table.
The calibrating table may comprise a base, housing or machine structure upon which a support or mounting platform is vertically displaceable for alignment with the extruder and can carry sizing or calibrating members, generally operated under vacuum or suction to draw walls of the extrusion against the calibrating or sizing surfaces and thereby prevent collapse of the extrusion during the cooling and solidifying stage. The calibrator imparts nuances of size and shape to the extrusions and the solidified body which emerges has sufficient cohesion, tensile strength and compressive strength to enable the resulting extruded body to be handled.
To draw the extrusion or extruded body through the calibrator, a track-type hauler may be provided downstream of the calibrating table. The hauler may have a pair of tracks or caterpillars, each of which extends longitudinally in the longitudinal direction of the extruded profile and comprises a pair of endless tracks mounted on sprockets which are spaced apart in the direction in which the profile is drawn. The chains forming the tracks carry pads which grip the profile between them and advance the profile through a gap between the tracks.
In such systems, the calibrator table and the hauler can be fixed on respective bases. It has been found, however, that the pulling force of the hauler, when applied indirectly to the calibrating devices on the calibrating frame, may cause fluctuating movements of that frame in the hauling direction. Accordingly, variations in the extruded body can result which may be detrimental or at least can cause problems where substantial uniformity is necessary, e.g. in the case of window-forming profiles.
In spite of the presence of the calibrator in such cases, moreover, the wall thickness of the product may vary.
In addition, it is difficult with prior art systems of the aforedescribed type, to gain precise information with respect to the force with which the hauler acts upon the extruded body.
In the drawing of the profile body by the hauler, therefore, forces are applied to the calibrator and cooler support frame which vibrates during the process as these forces are applied to the devices provided for vertically adjusting the frame. The vibration is detrimental to the quality of the profiled body which is produced and the precision with which the product is formed. It also may detrimentally affect surface quality of the profile body. One of the characteristics of these earlier systems is that unacceptable marking of the surface can occur as a result of these vibrations.
The so-marked and so-affected extrusions must be discarded.